And that is: if you've had a small grandson in the back of your car, do check that he hasn't left the window open before you take it through the car wash.
I don't like car washes at the best of times. They make me sick and disorientated. And when water(?) began to put through a back window, it took me some time to close the window. Now, the back seat is soaked, and I am drenched in what could be either water, soap, or polish. Whatever it is, it tastes funny.
Other grandparents: take note.